examples/awesome/_static/mermaid.css

html .mermaid > svg {
  display: block;
  margin: 0 auto;
  filter: invert(1);
}
@media (prefers-color-scheme: dark) {
  html:not(.light-mode) .mermaid > svg {
    filter: invert(0);
  }
}
html.dark-mode .mermaid > svg {
  filter: invert(0);
}